Homozygous deletions within the 11q13 cervical cancer tumor‐suppressor locus in radiation‐induced, neoplastically transformed human hybrid cells

Abstract

Studies on nontumorigenic and tumorigenic human cell hybrids derived from the fusion of HeLa (a cervical cancer cell line) with GM00077 (a normal skin fibroblast cell line) have demonstrated "functional" tumor-suppressor activity on chromosome 11. It has been shown that several of the neoplastically transformed radiation-induced hybrid cells called GIMs (gamma ray induced mutants), isolated from the nontumorigenic CGL1 cells, have lost one copy of the fibroblast chromosome 11. We hypothesized, therefore, that the remaining copy of the gene might be mutated in the cytogenetically intact copy of fibroblast chromosome 11. Because a cervical cancer tumor suppressor locus has been localized to chromosome band 11q13, we performed deletion-mapping analysis of eight different GIMs using a total of 32 different polymorphic and microsatellite markers on the long arm (q arm) of chromosome 11. Four irradiated, nontumorigenic hybrid cell lines, called CONs, were also analyzed. Allelic deletion was ascertained by the loss of a fibroblast allele in the hybrid cell lines. The analysis confirmed the loss of a fibroblast chromosome 11 in five of the GIMs. Further, homozygous deletion (complete loss) of chromosome band 11q13 band sequences, including that of D11S913, was observed in two of the GIMs. Detailed mapping with genomic sequences localized the homozygous deletion to a 5.7-kb interval between EST AW167735 and EST F05086. Southern blot hybridization using genomic DNA probes from the D11S913 locus confirmed the existence of homozygous deletion in the two GIM cell lines. Additionally, PCR analysis showed a reduction in signal intensity for a marker mapped 31 kb centromeric of D11S913 in four other GIMs. Finally, Northern blot hybridization with the genomic probes revealed the presence of a novel >15-kb transcript in six of the GIMs. These transcripts were not observed in the nontumorigenic hybrid cell lines. Because the chromosome 11q13 band deletions in the tumorigenic hybrid cell lines overlapped with the minimal deletion in cervical cancer, the data suggest that the same gene may be involved in the development of cervical cancer and in radiation-induced carcinogenesis. We propose that a gene localized in proximity to the homozygous deletion is the candidate tumor-suppressor gene.

One in four individuals of African-American ancestry harbors a 5.5 kb deletion at chromosome 11q13.1

“…Thus, the HeLa cells showed homozygous loss of the 5.5kb sequences. HeLa cell derived tumorigenic hybrid cell lines and a primary cervical tumor also showed homozygous loss of these sequences (represented by the STS marker D11S913) [3]. Surprisingly, we also found heterozygous loss of the same sequences in two fibroblast cell lines (GM00077 and GM00468).…”

“…We have previously localized the HeLa cell homozygous deletion to a ~5.5kb interval of chromosome 11q13.1 [3] (Figure 1). While one of the deletions was 5.5kb, the other deletion was 2.3Mb.…”

Dysregulation of hsa-miR-34a and hsa-miR-449a leads to overexpression of PACS-1 and loss of DNA damage response (DDR) in cervical cancer

“…We and others have shown that a cervical cancer tumor suppressor gene is localized to chromosome 11q13 and that genomic rearrangements at this site are common in cervical and other human cancers (13,14). We have further shown that homozygous deletion of 5.5kb is seen in HeLa cell derived tumorigenic cell lines and primary tumors indicating the importance of these sequences in tumor development (15)(16)(17). Extensive mapping of the 300kb region localized the 5.5 kb sequence to the 1 st intron of PACS-1, a protein involved in cytoplasmic protein trafficking (15)(16)(17).…”

“…We have further shown that homozygous deletion of 5.5kb is seen in HeLa cell derived tumorigenic cell lines and primary tumors indicating the importance of these sequences in tumor development (15)(16)(17). Extensive mapping of the 300kb region localized the 5.5 kb sequence to the 1 st intron of PACS-1, a protein involved in cytoplasmic protein trafficking (15)(16)(17). The repetitive nature of the 5.5 kb sequence made it extremely difficult to functionally characterize the sequence for its role in tumor development.…”

Inactivation of the cystatin E/M tumor suppressor gene in cervical cancer

“…We and others have confirmed the involvement of chromosome 11 in cervical cancer by suppression of the tumorigenic phenotype with the transfer of chromosome 11 into cervical cancer cell lines (Saxon et al, 1986; Koi et al, 1989). Detailed cytogenetic and molecular genetic analysis of cervical cancer cell lines, non tumorigenic and tumorigenic HeLa cell hybrids, and primary tumors localized the gene to a 300 kb interval of 11q13 (Jesudasan et al, 1995; Srivatsan et al, 2002; Mendonca et al, 2004). CGH (comparative genomic hybridization) and SKY (spectral karyotyping) studies have identified translocations and amplifications at chromosome 11q13 in cervical cancer lines (Harris et al, 2003; Rao et al, 2004).…”